feat: introduce createLanguageDetector

[jakex7]

Introduce createLanguageDetector to provide greater flexibility with language detection. This change means the current detector (ReactNativeLanguageDetector) will be deprecated in favor of the more adaptable option.

Usage:

import { createLanguageDetector } from 'react-native-localization-settings';

const languageDetector = createLanguageDetector();

i18next
  .use(languageDetector)
  .init({});